Current feedback based voltage regulator for non-volatile memories

Abstract

Non-volatile memories have continued to retrieve their stronghold presence in the electronic industry wherever memory intensive applications are required. The present technologies like Flash have dominated the industry for so long. However there is a continuous shrinking of the technology nodes and now reaching the edge. This shrinking leads to challenging design of the floating gate devices used in Flash memories. The number of electrons stored in the floating gate decreases. As a result, there is a continuous focus on emerging trends and solutions to replace the existing technologies. Phase change memories (PCM) have shown a growing trend in the recent years. It exploits the concept of the phase transition of a chalcogenide material from amorphous to crystalline. PCM characteristics approximate those of DRAM and Flash memories, making it their strong competitor. Its main advantages are large cycling endurance, fast program and access time and extended scalability. In this dissertation, a voltage regulator has been developed in 110nm BCD9s technology for high voltage management with reference to phase change memory system. The error amplifier of the regulator is a three-stage operational amplifier designed to achieve a high gain with a sufficient phase margin. The voltage regulator is capable of regulating a wide voltage range, which is made possible by using a current based feedback system for the regulator. The varying current feedback enables to vary the feedback to the opamp, providing a variable regulation scheme. The regulator provides a minimum granularity of 100 mV starting from 1.2 V onwards. The feedback current has a minimum granularity of 1 μA supporting the 100 mV step of the regulator.